ProxyFileDescriptorCallback

Kotlin |Java

public abstract class ProxyFileDescriptorCallback
extends Object

java.lang.Object
↳	android.os.ProxyFileDescriptorCallback

Callback that handles file system requests from ProxyFileDescriptor. All callback methods except for onRelease should throw ErrnoException with proper errno on errors. See errno(3) and OsConstants. Typical errnos are

OsConstants.EIO for general I/O issues
OsConstants.ENOENT when the file is not found
OsConstants.EBADF if the file doesn't allow read/write operations based on how it was opened. (For example, trying to write a file that was opened read-only.)
OsConstants.ENOSPC if you cannot handle a write operation to space/quota limitations.

See also:

StorageManager.openProxyFileDescriptor(int, ProxyFileDescriptorCallback, Handler)

Summary

Public constructors
`ProxyFileDescriptorCallback()`

Public methods
`void`	`onFsync()` Ensures all the written data are stored in permanent storage device.
`long`	`onGetSize()` Returns size of bytes provided by the file descriptor.
`int`	`onRead(long offset, int size, byte[] data)` Provides bytes read from file descriptor.
`abstract void`	`onRelease()` Invoked after the file is closed.
`int`	`onWrite(long offset, int size, byte[] data)` Handles bytes written to file descriptor.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

ProxyFileDescriptorCallback

public ProxyFileDescriptorCallback ()

Public methods

onFsync

Added in API level 26

public void onFsync ()

Ensures all the written data are stored in permanent storage device. For example, if it has data stored in on memory cache, it needs to flush data to storage device.

Throws
`ErrnoException`	ErrnoException containing E constants in OsConstants.

onGetSize

Added in API level 26

public long onGetSize ()

Returns size of bytes provided by the file descriptor.

Returns
`long`	Size of bytes.

Throws
`ErrnoException`	ErrnoException containing E constants in OsConstants.

onRead

Added in API level 26

public int onRead (long offset, 
                int size, 
                byte[] data)

Provides bytes read from file descriptor. It needs to return exact requested size of bytes unless it reaches file end.

Parameters
`offset`	`long`: Offset in bytes from the file head specifying where to read bytes. If a seek operation is conducted on the file descriptor, then a read operation is requested, the offset refrects the proper position of requested bytes.
`size`	`int`: Size for read bytes.
`data`	`byte`: Byte array to store read bytes.

Returns
`int`	Size of bytes returned by the function.

Throws
`ErrnoException`	ErrnoException containing E constants in OsConstants.

onRelease

Added in API level 26

public abstract void onRelease ()

Invoked after the file is closed.

onWrite

Added in API level 26

public int onWrite (long offset, 
                int size, 
                byte[] data)

Handles bytes written to file descriptor.

Parameters
`offset`	`long`: Offset in bytes from the file head specifying where to write bytes. If a seek operation is conducted on the file descriptor, then a write operation is requested, the offset refrects the proper position of requested bytes.
`size`	`int`: Size for write bytes.
`data`	`byte`: Byte array to be written to somewhere.

Returns
`int`	Size of bytes processed by the function.

Throws
`ErrnoException`	ErrnoException containing E constants in OsConstants.